Dual turbo centrifugal chiller

ABSTRACT

A dual turbo centrifugal chiller includes: first and second evaporators connected in series or in parallel; first and second condensers connected in series or in parallel; and first and second compressors including impellers, wherein cold water passes through the second evaporator after passing through the first evaporator, and cooling water passes through the second condenser after passing through the first condenser, the first compressor containing a refrigerant connects the first condenser to the second evaporator, and the second compressor containing a refrigerant connects the second condenser to the first evaporator, and the impellers of the first compressor and second compressor are rotated simultaneously using a single driving unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No.10-2009-0102209, filed on Oct. 27, 2009, and all the benefits accruingtherefrom under 35 U.S.C. §119, the contents of which in its entiretyare herein incorporated by reference.

BACKGROUND

1. Field

This disclosure relates to a dual turbo centrifugal chiller,particularly to a dual turbo centrifugal chiller configured to decreasehead of a compressor among components of two individual chillers,decrease the size of the chiller, and increase efficiency.

2. Description of the Related Art

A general chiller includes a compressor, an evaporator, a condenser, andan expansion valve, and circulates a refrigerant to transfer heat fromthe evaporator to the condenser through heat exchange.

FIG. 1 is a diagram schematically illustrating a general chiller 10.

As illustrated in FIG. 1, the chiller 10 includes an evaporator 30, acondenser 20, and a compressor 40. Cold water 31 flows through theevaporator 30, and cooling water 21 flow through the condenser 20.

The compressor 40 in which a refrigerant 51, 52 is circulated connectsthe evaporator 30 to the condenser 20. The refrigerant 51 that passesthrough the evaporator 30 flows into the compressor 40 through an inletportion 47 of the compressor 40, and the refrigerant 52 compressed bytwo-stage impellers 41 and 42 flows out of an outlet portion 48 of thecompressor 40 and then flows into the condenser 20.

As illustrated in FIG. 1, in the compressor 40, the two-stage impellers41 and 42 are provided on a shaft 43, and the impellers 41 and 42 arerotated as the shaft 43 is rotated by a motor 45. Here, gears 44 and 46are provided to connect the motor 45 to the shaft 43 so as to transmittorque. Although not shown in the figure, a thrust bearing may beconnected between the gear 44 and the shaft 43.

In the general compressor 40, a load applied to the bearing increasesbecause a thrust that is transferred to the gears 46 and 44 is focusedin one direction, and, thus, a load applied to the motor 45 alsoincreases. As the load applied to the motor 45 increases, an outlettemperature of the cold water increases, which results in an increase inhead of the compressor. As a result, the efficiency of the compressor isdecreased.

In order to decrease the head of the compressor and increase theefficiency of the chiller, a ‘dual turbo centrifugal chiller’ whichincludes two chillers connected to each other has been used. The dualturbo centrifugal chiller has an increased capacity by increasing thechilling efficiency of the chiller itself. In the dual turbo centrifugalchiller, two compressors are provided. However, in the existing dualturbo centrifugal chiller, one of the two compressors has a higher headthan the other. Therefore, the two compressors have to be independentlydesigned and manufactured. That is, a driving unit for driving animpeller of each of the compressors is additionally needed, and theentire size of the chiller is increased. Accordingly, as describedabove, there is a problem in that the efficiency of the compressor isdecreased.

SUMMARY

This disclosure provides a dual turbo centrifugal chiller in which twocompressors, two evaporators, and two condensers are included todecrease heads of the compressors, the compressors are configured tooperate with the same head, and impellers of the compressors are drivenby a single driving unit, thereby achieving a decrease in size and anincrease in efficiency.

In one aspect, there is a provided a dual turbo centrifugal chillerincluding: first and second evaporators connected in series or inparallel; first and second condensers connected in series or inparallel; and first and second compressors including impellers, whereincold water passes through the second evaporator after passing throughthe first evaporator, and cooling water passes through the secondcondenser after passing through the first condenser, the firstcompressor containing a refrigerant connects the first condenser to thesecond evaporator, and the second compressor containing a refrigerantconnects the second condenser to the first evaporator, and the impellersof the first compressor and the second compressor are rotatedsimultaneously using a single driving unit.

In addition, the impellers of the first and second compressors may beconnected with a single rotation shaft, and the impellers of the firstand second compressors may be rotated simultaneously as the rotationshaft is rotated using the driving unit.

In addition, the driving unit may be connected to the center of therotation shaft, and the impellers of the first and second compressorsmay be opposed with the center of the rotation shaft between them.

In addition, inlet portions of the first and second compressors may beprovided with inlet guide vanes (IGVs) respectively.

In addition, the first and second compressors may have differentcapacities from each other.

Since the dual turbo centrifugal chiller including the two evaporators,the two compressors and the two condensers maintains the reduced head ofeach compressor, it is possible to achieve the optimal performance ofthe compressor.

In addition, since the impellers of the two compressors are drivensimultaneously using the single driving unit, it is possible toimplement the compressor having a small size and high efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the disclosedexemplary embodiments will be more apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a diagram schematically illustrating a general chiller;

FIG. 2 is a diagram schematically illustrating a dual turbo centrifugalchiller according to an embodiment; and

FIG. 3 is a diagram schematically illustrating a dual turbo centrifugalchiller according to another embodiment.

DETAILED DESCRIPTION

Exemplary embodiments now will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsare shown. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to the exemplaryembodiments set forth therein. Rather, these exemplary embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of this disclosure to those skilled in the art.In the description, details of well-known features and techniques may beomitted to avoid unnecessarily obscuring the presented embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of this disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. Furthermore, the use of the terms a, an, etc. does not denotea limitation of quantity, but rather denotes the presence of at leastone of the referenced item. It will be further understood that the terms“comprises” and/or “comprising”, or “includes” and/or “including” whenused in this specification, specify the presence of stated features,regions, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art. It will be further understood that terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and the present disclosure, and will notbe interpreted in an idealized or overly formal sense unless expresslyso defined herein.

In the drawings, like reference numerals in the drawings denote likeelements. The shape, size and regions, and the like, of the drawing maybe exaggerated for clarity.

FIG. 2 is a diagram schematically illustrating a dual turbo centrifugalchiller 101 according to an embodiment.

As illustrated in FIG. 2, according to the embodiment, a firstevaporator 121 and a second evaporator 122 are connected in series. Coldwater 123 flows into an end of the first evaporator 121 connected inseries, passes through the first evaporator 121, passes through thesecond evaporator 122, and then flows out.

A first condenser 111 and a second condenser 112 are connected inseries. Cooling water 113 passes through the first condenser 111, flowsinto the second condenser 112, passes through the second condenser 112,and then flows out.

A first compressor 131 is connected to the first condenser 111 and thesecond evaporator 122 such that a refrigerant of the first compressor131 is circulated to exchange heat with the cooling water 113 of thefirst condenser 111 and the cold water 123 of the second evaporator 122.A second compressor 132 is connected to the second condenser 112 and thefirst evaporator 121 such that a refrigerant of the second compressor132 is circulated to exchange heat with the cooling water 113 of thesecond compressor 112 and the cold water 123 of the first evaporator121.

A temperature of the cold water that flows into the first evaporator 121is 12° C., a temperature of the cold water that flows out of the secondevaporator 122 is 7° C., a temperature of the cooling water that flowsinto the first condenser 111 is 32° C., and a temperature of the coolingwater that flows out of the second condenser 112 is 37° C.

Without consideration of leaving temperature differences (LTDs) of theevaporator and the condenser, a head of the first compressor 131 is27.5° C. (34.5° C.-7° C.), and a head of the second compressor 132 isalso 27.5° C. (37° C.-9.5° C.).

In the dual turbo centrifugal chiller 101 according to the embodiment,as described above, the heads of the two compressors 131 and 132 areequal to each other. Accordingly, as described below, a design forsimultaneously driving impellers of the two compressors using a singledriving unit may be easily achieved.

Hereinafter, configurations of the two compressors 131 and 132 accordingto the embodiment will be described with reference to FIG. 2.

According to the embodiment, the first compressor 131 is a two-stagecompression system having two impellers 145 and 146. A refrigerant 151flows out of the second evaporator 122 into the first compressor 131through an inlet portion 141 of the first compressor 131, and therefrigerant is compressed while passing through the impellers 145 and146. The compressed refrigerant 152 flows out of the first compressor131 through an outlet portion 142 and flows into the first condenser111.

The second compressor 132 is a two-stage compression system having twoimpellers 143 and 144. A refrigerant 153 that flows out of the firstevaporator 121 flows into the second compressor 132 through an inletportion 143 of the second compressor 132, and the refrigerant iscompressed while passing through the impellers 143 and 144. Thecompressed refrigerant 154 flows out of the second compressor 132through an outlet portion 144 and flows into the second condenser 122.

According to the embodiment, a single driving unit 163 for rotating theimpellers 143, 144, 145, and 146 of the two compressors 131 and 132 isprovided. In this embodiment, an electric motor is used as the drivingunit 163.

The impellers 143, 144, 145, and 146 of the two compressors 131 and 132are connected with a rotation shaft 161. A gear 162 is provided at thecenter of the rotation shaft 161, the impellers 145 and 146 of the firstcompressor 131 and the impellers 143 and 144 of the second compressor132 are opposed with the center of the rotation shaft 161 between them.An end portion of the driving unit 163 is connected to a gear, and thegear connected to the driving unit 163 is engaged with a gear 162 of therotation shaft 161. In this configuration, the single driving unit 163rotates the rotation shaft 161, and as the rotation shaft 161 isrotated, the impellers 143, 144, 145, and 146 of the two compressors 131and 132 are rotated simultaneously.

According to the embodiment, since the two individual compressors 131and 132 are driven by the single driving unit 163, the entire volume ofthe compressor system is reduced. Therefore, the entire size of the dualturbo centrifugal chiller 101 is reduced.

In addition, since the impellers of the two compressors are disposedsymmetrically, thrusts applied to both ends of the gear 162 occur in theopposite direction and cancel each other out. Accordingly, a loadapplied to a bearing (not shown) used for the gear 162 decreases, whichresults in a decrease in the load applied to the driving unit 163 and anincrease in the efficiency of the driving unit 163. The increase in theefficiency of the driving unit 163 causes a decrease in the outlettemperature of the cooling water, and this causes a decrease in theheads of the compressors 131 and 132. Accordingly, there are advantagesin that the efficiency of the entire compression system increases, andthe efficiency of the entire chiller increases. In addition, indesigning the bearing, a design of the bearing without concern about thethrust applied in particular direction may be achieved.

According to the embodiment, the inlet portions of the first and secondcompressors 131 and 132 are provided with inlet guide vanes (IGVs) foradjusting loads applied thereto in order to facilitate load adjustment.

According to the embodiment, since the first and second compressors 131and 132 are separated from each other, various combinations of capacitymay be attained with the compressors and the heat exchangers (thecondensers and the evaporators). For example, the capacities of thecompressors 131 and 132 may be set to 1,000 RT and 500 RT, respectively.The size of the heat exchanger is determined according to the capacityof the compressor. Even in this case, the impellers of the compressorsare disposed symmetrically on the single rotation shaft, and since theimpellers are disposed symmetrically, the thrust cancellation effect ofthe bearing is exhibited even in the case where the capacities of thetwo compressors are different from each other.

In this embodiment, the two evaporators 121 and 122 are connected inseries, and the two condensers 111 and 112 are connected in series,however, the embodiment is not limited to that configuration.Hereinafter, another embodiment will be described with reference to FIG.3.

FIG. 3 is a diagram schematically illustrating a dual turbo centrifugalchiller 201 according to another embodiment.

As illustrated in FIG. 3, in the dual turbo centrifugal chiller 201according to this embodiment, a first evaporator 221 and a secondevaporator 222 are connected in parallel. Cold water 223 flows into anend of the first evaporator 221 connected in parallel and flows out ofthe other end of the first evaporator 221, flows into an end of thesecond evaporator 222, passes through the second evaporator 222, andflows out of the other end of the second evaporator 222.

A first condenser 211 and a second condenser 212 are connected inparallel. Cooling water 213 flows into an end of the first condenser 211connected in parallel, flows out of the other end of the first condenser211, flows into an end of the second condenser 212, passes through thesecond condenser 212, and flows out of the other end of the secondcondenser 212.

A first compressor 231 is connected to the first condenser 211 and thesecond evaporator 222, and a refrigerant of the first compressor 231 iscirculated to exchange heat with the cooling water of the firstcondenser 211 and the cold water of the second evaporator 222. A secondcompressor 232 is connected to the second condenser 212 and the firstevaporator 221, and a refrigerant of the second compressor 232 iscirculated to exchange heat with the cooling water of the secondcondenser 212 and the cold water of the first evaporator 221.

Here, a temperature of the cold water that flows into the firstevaporator 221 is 12° C., a temperature of the cold water that flows outof the second evaporator 222 is 7° C., a temperature of the coolingwater that flows into the first condenser 211 is 32° C., and atemperature of the cooling water that flows out of the second condenser212 is 37° C.

Without consideration of LTDs of the evaporators and the compressors, ahead of the first compressor 231 is 27.5° C. (34.5° C.-7° C.), and ahead of the second compressor 232 is also 27.5° C. (37° C.-9.5° C.).That is, the heads of the two compressors are equal to each other.

Since connection relationships between impellers 245, 246, 247, and 248of the compressors 231 and 232, the rotation shaft 161, a gear 262, anda driving unit 263 provided in the dual turbo centrifugal chiller 201according to this embodiment, and a flow of a refrigerant 251, 252, 253,and 254 at inlet and outlet portions 243 and 244 of the compressor arethe same as those of the embodiment illustrated in FIG. 2, a detaileddescription thereof will be omitted.

Although the two embodiments of the dual turbo centrifugal chiller havebeen described, this disclosure is not limited thereto. That is to say,the two evaporators may be connected in serial or in parallel, and thetwo condensers may be connected in serial or in parallel. In this case,it should be understood by those skilled in the art that cold waterpasses through a first evaporator and a second evaporator, cooling waterpasses through a second condenser after passing through a firstcondenser, a first compressor containing a refrigerant is connected tothe first condenser and the second evaporator, and a second compressorcontaining a refrigerant is connected to the second condenser and thefirst evaporator, thereby implementing a dual turbo centrifugal chillerin which heads of the two compressor are equal to each other.

While the exemplary embodiments have been shown and described, it willbe understood by those skilled in the art that various changes in formand details may be made thereto without departing from the spirit andscope of this disclosure as defined by the appended claims.

In addition, many modifications can be made to adapt a particularsituation or material to the teachings of this disclosure withoutdeparting from the essential scope thereof. Therefore, it is intendedthat this disclosure not be limited to the particular exemplaryembodiments disclosed as the best mode contemplated for carrying outthis disclosure, but that this disclosure will include all embodimentsfalling within the scope of the appended claims.

1. A dual turbo centrifugal chiller, comprising: first and secondevaporators connected in series or in parallel; first and secondcondensers connected in series or in parallel; and first and secondcompressors including impellers, wherein cold water passes through thesecond evaporator after passing through the first evaporator, andcooling water passes through the second condenser after passing throughthe first condenser, the first compressor containing a refrigerantconnects the first condenser to the second evaporator, and the secondcompressor containing a refrigerant connects the second condenser to thefirst evaporator, and the impellers of the first compressor and secondcompressor are rotated simultaneously using a single driving unit. 2.The dual turbo centrifugal chiller according to claim 1, wherein theimpellers of the first and second compressors are connected with asingle rotation shaft, and the impellers of the first and secondcompressor are rotated simultaneously as the rotation shaft is rotatedusing the driving unit.
 3. The dual turbo centrifugal chiller accordingto claim 2, wherein the driving unit is connected to the center of therotation shaft, and the impellers of the first and second compressorsare opposed with the center of the rotation shaft between them.
 4. Thedual turbo centrifugal chiller according to claim 1, wherein inletportions of the first and second compressors are provided with inletguide vanes (IGVs) respectively.
 5. The dual turbo centrifugal chilleraccording to claim 3, wherein the first and second compressors havedifferent capacities from each other.